Temperature controlled martensitic phase transformations in a model NiAl alloy

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Tourism and water inequity in Bali: A social-ecological systems analysis

This paper is a social-ecological systems (SES) analysis of tourism and water inequity in Bali. It uses Elinor Ostrom’s SES model to look at the particular niche of Bali’s tourism and water nexus. Re-analysis of previous qualitative research revealed that the vulnerability of the SES was due to numerous characteristics. In particular, user groups are highly diverse, transient and stratified, thereby inhibiting communication and knowledge sharing. This, in combination with weak governance systems and the economic power of the tourism industry, interact to affect declining water resources and the iniquitous impact of this. Whilst there are obvious indications that Bali’s water resources are over stretched, there is no feedback loop to the institutional structures that would help enable appropriate responses from the user groups or governance system

Transformation de phase dans l'aluminium induite par implantation ionique de nickel à haute énergie

Implantation of Ni into a pure Al target leads to the formation of amorphous zones. Their formation is studied by transmission electron microscopy (TEM). The present results were obtained in samples implanted with ions having energies between 22 and 40 MeV and fluences between 1.68x1015 and 2.5x1017 ions/cm2. In order to observe the profile of the ion implantation in the TEM, cross-sectional samples were thinned with a specially modified ion bombardement. Measurements of the atomic concentration have been carried out with energy dispersive spectroscopy (EDS). In spite of the Ni concentration (up to 3 at. %) in the implanted layer, there is no observable nuclei of the Al3Ni phase after implantation at 120 K and room temperature. In contrary, amorphous zones with a diameter of about 10 nm are present together with a high density of dislocation loops and dislocations. The Ni concentration in the amorphous zones is about 25 at. %. An implantation conducted at 520 K shows only crystalline precipitates of Al3Ni. We conclude that the Ni implanted in Al agglomerates in zones having composition identical to that of the Al3Ni phase

Stability of helium bubbles in alpha-iron: A molecular dynamics study

Molecular dynamics simulations were performed to estimate the dissociation energies of helium interstitials, vacancies and self-interstitial atoms from small helium-vacancy clusters. Several sets of empirical potentials have been tested and compared with available ab initio calculations in order to provide the best combination of potentials to study the stability of small helium bubbles. The behavior of the cluster seems to be better described using Ackland potential for the Fe-Fe interactions and Juslin potential for the Fe-He interactions. From the calculations, it appears that the dissociation energies mainly depend on the helium-to-vacancy ratio rather than the cluster size, The helium/vacancy crossover slightly varies with increasing number of vacancies, but the crossover defining the loop-punching regime decreases strongly with increasing cluster sizes. (C) 2009 Elsevier B.V. All rights reserved